reaction that might be linked to the vaccine. here's lisa stark. >> reporter: in a washington, d.c. conference room today, experts from around the country gathered to scour for even the smallest clues that the h1n1 vaccine is causing dangerous reactions. dr. bruce gellin is the government's point man on vaccines, and says of the over millions who have received the vaccine so far there have been only 302 reported side effects. >> mostly sore arms, malaise, fever, things like that. >> reporter: so nothing that "uh-oh, this vaccine may not be safe." >> we're looking hard. we have many different systems in place. so far, we haven't seen anything that worries us. >> reporter: the government's massive surveillance effort involves cross checking lists of those who have received the vaccine with any later reports of health problems. data will come from health records from the department of defense, veteran affairs, the indian health service, medicare, and even from private health care plans covering 20 million americans. doctors and the public can also report side effects to a government